This invention relates generally to a system combining a water heater tank with a refrigeration unit in a manner whereby energy for heating the water is extracted from the unit, and more particularly to a thermally integrated system of this type in which the heat dissipated by the refrigeration unit is fully exploited, yet its efficiency is maintained despite changing temperatures in the water tank.
There are many facilities which require a refrigeration unit as well as a hot water source. Thus the typical restaurant must have one or more refrigerator units in which to refrigerate vegetables, meats and liquids, and it must also have a hot water supply to carry out various cleaning operations.
In the usual restaurant installation, an electrically-energized refrigerator unit is operated in a manner totally independent of the water heater, as a consequence of which heat removed in the condensing process is wasted. And where the removed heat is not discharged through an exterior vent but into the area in which the refrigeration unit is installed, this heat may impose an additional load on an air conditioning system operating in that area. On the other hand, the conventional water heater is energized by a gas, oil, or electrical supply. Where the demand for heated water is high, the energy costs therefor are substantial.
The concept of extracting heat from a refrigeration unit for the purpose of heating the water in a water heater is well known in the art. Thus in the 1979 patent to Amthor, Jr., U.S. Pat. No. 4,173,872, the condenser coil of a refrigeration unit is disposed within a water tank and serves to raise the temperature of the water therein. Arrangements along similar lines are disclosed in the patents to Hammell, U.S. Pat. No. 2,668,402; Johnson, U.S. Pat. No. 4,178,769; Mueller, U.S. Pat. No. 4,146,089 and Eggleston, U.S. Pat. No. 2,125,842.
While the arrangements disclosed in these prior patents serve to utilize otherwise wasted energy, they fail to fully and effectively exploit the available heat energy and make no adequate provision to maintain efficient operation of the refrigeration unit under optimum conditions regardless of the changing demand for hot water normally experienced in a restaurant or similar facility.
For example, if the condenser coil of the refrigeration unit is disposed within the water tank in heat exchange relation with the water therein, and no water is withdrawn from the tank for a prolonged period, the rising temperature of the water in the tank will approach the temperature of the refrigerant passing through the coil. As a consequence, a proper condensing action will not take place, causing the refrigerator unit to automatically cut off.
If, on the other hand, heated water is continuously drawn from the water tank so that the temperature of the water in the tank begins to approach the relatively low temperature of incoming water replenishing the water withdrawn from the tank, then an excessive condensing action will take place which will interfere with the proper operation of the refrigeration unit.